England captain Michael Vaughan and his South African counterpart Graeme Smith will be hoping to fire in a crucial World Cup Super Eights match here on Tuesday.

England and South Africa expect their captains to lead from the front in a match they need to win to stay in contention for the semi-finals. South Africa have six points from six matches and England four from five.

Defending champions Australia and New Zealand have already qualified for the semi-finals with 10 points. Sri Lanka are also through leaving just one place up for grabs.

A stiff test awaits struggling Vaughan and Smith on a Kensington Oval track having pace and bounce as both teams boast of quality fast bowlers capable of probing the best on helpful pitches.

England have been struggling for big starts as Vaughan is looking out of form at the top of the order. He has scored only 113 runs in seven matches and is still without a half-century.

The South African captain started on an impressive note when he smashed four successive half-centuries, but lost his way in the Super Eights. He has scored only 20 in his last three games.

A solid start will be required to seize the initiative on the pace-friendly pitch, and the onus is now on Vaughan and Smith to put their teams' campaigns back on the tracks.

"It is a mixture of reasons for the struggle at the top of the order and definitely form is one of those. We need to spend some time in the centre. We have to improve in some areas," said Vaughan.

England have been performing inconsistently in the second round as they have beaten only debutants Ireland and Bangladesh, and a defeat on Tuesday will end their chances of reaching the semi-finals.

They hardly looked at their best even during victories, especially against Bangladesh when they struggled to chase a modest 144-run target against left-arm spinners.

England have been relying on a couple of batsmen, with Kevin Pietersen, Ian Bell and all-rounder Paul Collingwood doing the bulk of scoring in most of the matches.

Andrew Flintoff's batting form only adds to England's problems ahead of the pressure match. The free-stroking batsman looked much below his best in the previous games, scoring 72 in six matches.

England have the satisfaction of finding Flintoff in an excellent bowling form as the paceman is his team's leading wicket-taker with 11. With fast bowlers James Anderson and Sajid Mahmood also enjoying success, England are expected to keep pressure on the South African batsmen.

Like England, South Africa also have been struggling for consistency in both batting and bowling departments. Their worst came when they suffered a shock defeat against Bangladesh in Guyana.

It seems South Africa have yet to recover from the shock as they yet again failed to lift their performance against New Zealand, losing by five wickets in a low-scoring match in Greneda on Saturday.

"It is a crunch game for us and it always was going to be. We'll bounce back. We have a lot of experience and we've got a lot of big players looking forward to the England game," said Smith.

South Africa's batting crumbled for the second time in three matches when they scored 193 against New Zealand, with Herschelle Gibbs alone acquitting himself well with a half-century.

Jacques Kallis is the lone batsman performing with consistency, having scored 463 runs in eight matches. But South Africa need more from other specialist batsmen in this game.